Method and means to protect sensitive eequipment from impact damages, and uses thereof

ABSTRACT

A method to protect sensitive equipment against impact damages is described, such as tools and instruments and the like which shall be lowered down in well pipes in a hydrocarbon-carrying formation, and it is characterised in that a layer of a protection means is put onto the equipment which is solid or partially solid when put on and also at the temperatures in an upper part of the well pipe, while it melts and become liquid and flows off the equipment at the temperatures that exist in the lower part of the well pipe where the equipment shall be applied. A protective means is described and also applications of this.

The present invention relates to a method to protect sensitive equipment against impact damages, such as tools and instruments and the like that shall be lowered down into well pipes in a hydrocarbon bearing formation.

Furthermore, the invention comprises a protection means to protect sensitive equipment against impact damages, and also preferred embodiments of thereof.

When one drills after oil and gas in formations, the bore hole that runs into and through the formation is designated as a well. Normally casing tubes are inserted against the walls in the well hole, before an independent production pipe is fed down in sections and fitted together and cemented to the casing/formation walls outside.

The casing protects the inner pipe and holds the surrounding formation in place so that it does not collapse into the well. Furthermore, it protects against unwanted inflow of fluids. In addition to the casing and the production pipe, control lines run down in the well and these carry signals to and from instruments and equipment down in the well. They have a small diameter with respect to the production pipe and normally lie between the casing and the production pipe, but are sometimes integrated into the casing itself or in the production pipe. The production pipe is positioned in the center of the well and leads oil and/or gas out of the formation that the well runs through.

Equipment that shall be led down in the well must thereby be lowered down through the production pipe or be fastened thereto before installation in the well.

Much of this equipment is very sensitive and can be damaged if it is subjected to blows. This can, for example, happen if the equipment hits the inner walls of the production pipe or other equipment fitted in the pipe, during the lowering of the equipment down the well. Damage can also occur to the equipment that is permanently fitted in the inner pipe. Then, other instruments and equipment that are lowered down or dropped down in the well can damage the permanently fitted equipment. This can be equipment that is lowered down and touches the permanently fitted equipment, or this can be due to equipment that drops uncontrollably into the well.

This can occur when work is carried out at the top of the well and parts or tools unintentionally drop down into the well.

An example of such sensitive equipment that can easily be damaged by falling objects or during the lowering down into the well are plug units that are used for pressure and leak testing of production pipes and casings. Such equipment comprises, but is not limited to, plugs, counting units, gliding casings, measuring apparatus, pressure and temperature measuring instruments, gaskets, casing hangers, nipple profiles, valves, bridge plugs, crushable plugs, soluble plugs such as salt plugs or other equipment or installations that need protection against falling objects. Counting units can, for example, be counting units connected to the pipe walls for the activation of plugs set up to be crushed in a controlled way, or to arrange for other equipment in a desired position in the well. Meant by plugs is both plugs that shall be installed permanently or plugs that shall be removed later, such as plugs that are used during pressure testing of wells.

Wells for oil and gas production are subjected to very high pressures that are due to a combination of atmospheric pressure (because of the depth of the well) and the pressure from the hydrocarbon-carrying layers in the formation.

Therefore, it is common that the production pipe must be able to withstand such pressure conditions and it is tested thoroughly for its ability to withstand pressure both before it is set in production and during the production or when changes are to be implemented. The tests relate to placing a plug down in the well, where the plug blocks for passage of fluids. Pressure is applied from the surface with the help of a suitable fluid such as drilling fluid and one checks for leaks by, for example, measuring pressure drop over time. When one has found the well pipe to be sufficiently leakproof, the plug is removed so that the well is opened and the production can start. The same goes for casing tubing that one will, in certain cases, have an overview of how leakproof they are with respect to the hydrocarbon-carrying formation lying outside the wells.

Plugs that are used for such well testing are well known in this field. They must be strong enough to be able to seal and close up the well completely and, at the same time, they must be removable—preferably quickly and, of course, without damaging the well. Most of the known solutions are plugs made from glass, but other materials that can easily be broken up, such as rubber, or be crushed, are also known. Glass or ceramic materials are suitable in plugs as they are resistant to such gases and liquids that exist in the wells, even at high pressures and high temperatures. Furthermore, they can be manufactured so that they tolerate a specific pressure load and can thereby be adapted to the specific conditions of a given well. At the same time glass and ceramic materials are easy to crush at predetermined conditions so that the plug is removed.

A glass or ceramic plug can be manufactured as a solid plug, or it can be made from several layers of glass/ceramics, possibly with other materials between the layers. Such materials can be solid materials, such as ceramic materials, plastic, felt or cardboard materials, but there can also be fluids in liquid or gas form between each glass layer. Areas or pockets with a lower pressure or vacuum can also be incorporated. The plug is normally placed in a seat in a holder in a separate pipe section which is set into the production pipe, pre-calculated to be placed at the right depth in the well. The section also comprises a device to crush the plug.

It is recommended that materials for such plugs have a factor of safety of 3, i.e. they shall withstand more than three times normal load before breaks occur in the plug.

When the plug is made from glass or other materials that can be, and are made to be, crushed, this can lead to problems. During the operation of the well, different objects, such as parts of production equipment or tools, can fall down into the well itself. When the plug is deep down in a production well, in the horizontal part of this, it is relatively safe as falling objects will not reach it, but in the upper, more vertical part of the well, falling objects represent a danger. One risks that the plug is damaged, as, in spite of it being able to tolerate high pressure, it does not tolerate any large mechanical load. The consequence of this is that one risks that the plug is opened at the wrong time so that the testing must be stopped. This is a risk with all plugs that are made from crushable materials such as glass and ceramic materials, although some types of plugs are more vulnerable than others. For example, plugs that are made up of several layers of glass, and in particular if they have fluids between the glass layers, as described in the Norwegian patent application NO-20061308, are particularly vulnerable, as it is enough that the top glass layer is damaged for the whole plug to become unstable and be damaged.

The plug described above is given as an example of equipment that is placed in an oil well that is subjected to damage when it, or other equipment, is moved in the well and then in particular if objects such as different tools or metal pieces fall down into the well. But other types of sensitive equipment are also exposed to this type of damage. It does not need to be made of glass to be damaged, if heavier objects or tools come in free fall in the production pipe they will quickly reach a speed that means even robust equipment made of, for example, metal or plastic, can be damaged. It is complicated to repair damaged equipment in the production pipe, so the damaged equipment must normally be hauled up from the well and be removed and replaced, or the operation must continue without it. Although there is a small chance that such damage arises, the consequences are serious, costly and can complicate further operation.

If said objects, such as instruments and tools, hit against, have hard and/or sharp points or edges (which then can hit with a large point load) and/or there is a large movement of motion (high speed and/or weight) the risk of damage is extra large.

When one shall lead tools and instruments that are small with respect to the pipe diameter, down in a production pipe, it can be difficult to keep them protected in the middle of the pipe so that they can easily impact against the pipe wall or other production equipment during the lowering down in the well.

With regard to prior art, reference is made to the US patent documents: U.S. Pat. No. 3,880,233; US-2011/0277988 and US-2009/0255686.

It is an aim of the invention to provide a new means to protect such instrumentation and tools that are in or shall be lowered down in a pipe (production pipe or casing tube) against damage as a result of collisions.

Furthermore, one aims to provide a solution to the problem this type of impact damage leads to.

In more detail, one wishes to ensure the instruments and tools in oil wells against unintended damage due to blows from falling objects, or that sensitive equipment that is lowered down via a string or the like hits against the production pipe or other equipment fitted in this pipe.

The method according to the invention is characterised in that a layer of a protection means is put on the equipment, which is solid or partially solid when put on and also at the temperatures in an upper part of the well pipe, while it melts and becomes liquid and flows off the equipment at the temperatures that exist in the lower part of the well pipe where the equipment shall be applied.

According to yet another preferred embodiment the layer of protection means is placed so that it covers at least an upper side of the equipment that shall be protected and preferably the whole of the outside of the equipment.

According to yet another preferred embodiment the protection means that covers the equipment is completely or partially covered by a flexible membrane or a further solid material. According to yet another preferred embodiment the protection means is covered by a further solid material in the form of a round disc adapted to the diameter dimensions of the production pipe.

According to yet another preferred embodiment the protection means that is put onto the equipment in the form of a viscous liquid is placed so that it is covered by the flexible membrane and/or the additional solid disc-formed material.

According to yet another preferred embodiment it is important that, when applied for protection equipment and instrumentation in a pipe section that supports a crushable plug, its release mechanism for crushing of the plug is covered by the protection means before the pipe section is lowered down in the well pipe.

According to yet another preferred embodiment the selection of a protection means is based on measurement and knowledge about the temperature profile for the formation the well pipe is driven through, as one chooses a protection means that is solid at the relevant temperature at the surface and in the upper part of the well pipe and which melts into a liquid-form when the equipment comes further down in the well and the formation.

According to yet another preferred embodiment protection means of different types of wax, fats or oils or mixtures of such, or metals or metal alloys are used, said means that are in a solid or partially solid form at the upper parts of the well, but which become liquid in the deeper parts of the well.

According to yet another preferred embodiment the protection means that is used is chosen from beeswax, carnauba wax, solid palm oil, stearin, or compositions of petroleum waxes such as paraffin waxes, or mixtures of such materials. Alternatively, a protection means is used that is chosen from tin (Sn), or alloys of different metals with a relatively low melting point, such as different eutectic alloys of one or more of the metals bismuth, lead, tin, indium and cadmium, Lipowitz alloy, cerrolow, Rose's metal and Field's metal.

The protection means is, in particular, chosen from plastic materials such as HDPE (polyethylene with a high density), LDPE (polyethylene with a low density), PP (polypropylene), PS (polystyrene) and PVC (polyvinylchloride).

The protection means according to the invention for the protection of sensitive equipment against impact damage, such as tools and instruments and the like that shall be lowered down in well pipes in a hydrocarbon-carrying formation, is characterised in that it is a material that is solid or partially solid at the temperatures in the upper part of the well pipe and liquid at the temperatures in the lower part of the oil well where the device that shall be protected shall be applied.

According to a preferred embodiment the choice of the production means is adapted to the temperature profile of the formation through which the well pipe is led, as one chooses a protection means that is solid at the temperature at the surface and in the upper part of the well pipe and which melts to liquid form when the appliance travels further down in the well.

According to yet another preferred embodiment it is composed of different types of wax, fats or oils or mixtures of such materials, or metals or metal alloys, the means are in a solid or partially solid form in the upper parts of the well, but which become liquid in the deeper parts of the well.

According to yet another preferred embodiment the protection means used is chosen from beeswax, carnauba wax, solid palm oil, stearin, or mixtures of petroleum waxes such as paraffin waxes or mixtures of such materials.

According to yet another preferred embodiment the protection means is metal, or alloys of different metals having a relatively low melting point, such as different eutectic alloys of one or more of the metals bismuth, lead, tin, indium and cadmium, Lipowitz alloy, cerrolow, Rose's metal and Field's metal.

According to yet another preferred embodiment the protection means is of plastic materials such as HDPE (polyethylene with a high density), LDPE (polyethylene with a low density), PP (polypropylene), PS (polystyrene) and PVC (polyvinylchloride).

According to yet another preferred embodiment the protection means is used to protect sensitive equipment that is placed in a production pipe in an oil well against damage from falling objects in the production pipe, and/or against damage from collisions with the production pipe or objects in this when the equipment is lowered in the well pipe.

In particular, the means is placed on the equipment before it is fed down the well pipe, either in connection with the production of the equipment or as a post-installation.

The means and the method are used to protect equipment that shall be led through a vertical part of the well pipe and further into a horizontal part of the well pipe where the equipment shall be fitted.

In particular, the means and the method used for the protection of sensitive equipment that is placed in a production pipe in an oil well, said equipment is a plug for pressure testing where said plug is preferably a glass or ceramic plug.

More Detailed Description Of The Invention.

It is common that an upper part of the boring of a production well is carried out vertically to turn or swing the drilling head in a more or less horizontal direction to reach, in an effective way, the oil/gas-containing layers that can be spread out some distance from and vertically below where the drilling rig is placed.

When the instrument or the tool that shall be protected shall be used in the horizontal part of the production well, it is largely only exposed to unintended damaging blows from falling objects during the lowering down itself through the vertical part of the well, but not when it is installed in the horizontal well part.

Temperature in wells.

The temperature in the well and the formation/rocky ground that one drills through increases the deeper one gets. The temperature and the drilling height can increase the further down in the well one gets. The temperature profile for a production well may increase from a temperature of about 40° C. at the upper layers of the well to a highest temperature of 200° C. in the lower layers. In a typical production well on the Norwegian shelf, the temperature at the lower part of the well will often lie in the area 60-130° C., while for wells with a high pressure and high temperature the temperature at the bottom is often as high as 200° C. The temperature in the upper part of the well is normally around 40° C.

By manufacturing a protection means of a material that is solid or partially solid at the temperature in the upper part and which goes into a liquid form at the temperatures in the lower part of the oil well, one achieves a protection means that can protect instruments and tools during the lowering down in the well while the means melts and flows off the object when it passes the given depth where the temperature rises above the melting point of the means. This is because the temperature rises on the way down.

When the protection means is in a solid or partially solid (softened) phase, all parts of the instrument and tool or their particularly vulnerable parts are encapsulated or covered by the protection means. This takes place at the surface before the instrument and items are led down into the well. They are thereby protected against damages from impacts from falling objects and collisions with other elements down in the well.

As the tools and instruments are lowered further and further down the well pipe and the temperature increases, the material melts, becomes liquid and can flow off so that the tool and the instruments are no longer protected but are free to be used in the well. An example can be the release mechanism that can be fitted in the pipe section that shall be lowered down during the fitting of the production pipe. Such impact sensitive constructions can then be covered by a protection means which then melts and flows off at a depth where the section shall be placed in the well. Before the material is melted and has flowed off, the release mechanism can not crush the plug or be detonated and the plug is thereby not crushed unintentionally.

As an example, a crushable plug in said pipe section can also be protected with a layer of protection means according to the invention to protect it against blows during the lowering down of the section with the plug. Or if the plug is fitted after the pipe section is fitted, it is covered by the means and is lowered down through the pipe and fitted at its adapted seat in the pipe section. And the means is chosen so that it melts away just before the plug arrives at the place of fitting.

Correspondingly, another instrumentation or tool can be protected in that a protection means in its solid form is put onto its surface. The means is adapted so that on the way down in the pipe it melts so that the instruments are ready to be used when they are in the location they will be applied.

When the instrumentation/tools are installed and made ready for use in that the material is melted away, they are, of course, no longer exposed to collision damage in that they are moved in the well, but they can still be damaged by falling objects or other equipment that moves or falls down in the well. If the instrumentation/tools are placed in a horizontally running part of the well, there is no danger for damage from falling objects. Falling objects will instead glide vertically and over in an arch-shape in direct contact with the pipe wall and into the horizontal or partially horizontal part of the pipe. Then, the pipe wall itself will take the impact of the collisions with the falling objects which then remain lying in the horizontal part of the pipe.

The material according to the invention, which is solid or partially solid at the temperatures in the upper part and liquid at the temperatures of the lower part of the oil well where the device that shall be protected shall be used, can be any material suitable for use in oil wells. Different materials can be chosen to protect different types of equipment, and be adapted to melt at a temperature that is optimal for the well in which it shall be used. With the use all the way down in the well with a very high temperature, for example, 200° C., one will, for example, chose a material that melts somewhat below this temperature, in this example at 100-200° C., while for installation of equipment higher up in the well where the temperature is lower, for example only 60° C., or in the bottom of the well with a lower temperature, such material will be unsuitable.

Therefore, the material must be chosen/adapted according to the temperature profile for the well it shall be used in. This profile is known before the drilling starts.

Selecting the material is a relatively technical issue when one knows what type of chemical conditions one can expect in the well, something which is known for different types of oil wells, and what kind of temperature one wants the material to melt at. The material can be completely solid or partially solid, in a paste form before it melts, but strong enough in its solid condition to withstand impacts from blows to protect apparatus and instrumentation.

Examples of preferred protection means are beeswax, carnauba wax, solid palm oil, stearin, or compositions of petroleum wax such as paraffin waxes. Beeswax has a melting temperature of 63° C., carnauba wax (palm wax) has a melting temperature of 83° C., solid palm oil has a melting point of 33-40° C., while stearin has typically a melting temperature of 72° C. These preferred means are thereby very applicable for the temperatures one finds in, for example, the normal oil wells in the North Sea. In a preferred embodiment the material is a fat, more preferred a wax. Different types of waxes can be adapted to have a desired consistency and melt at the temperature one requires and are not to be broken down when in contact with the fluids one finds in a well. When the wax melts and mixes with the content of the well this will not be damaging, it will only be thinned out and be removed with the other common liquids/fluids in the well.

According to another embodiment of the material of the invention it is preferred to use protection means in the form of metal mixtures/alloys with low melting points. This can be particularly ideal for very hot wells where one requires melting at a somewhat higher temperature than for the fat materials described above. For example, one can use tin (Sn), which has a melting temperature of 232° C. or alloys of different metals with a relatively low melting point, such as different eutectic alloys of one or more of the metals bismuth, lead, tin, indium and cadmium, Lipowitz alloy, which has a melting point of 70° C., cerrolow which depending on the specific type has a melting temperature of 40-70° C., Rose's metal, which has a melting temperature of 98° C., or Field's metal, which has a melting temperature of 62° C. But the invention is not limited to fats and metals, one can also use other materials that have a phase transition from solid or partially solid to liquid at the desired temperature, also other synthetically produced materials, such as plastic materials. Examples of suitable types of plastics are HDPE (polyethylene with a high density) with a melting point of about 130° C., LDPE (polyethylene with a low density) has a melting point of about 110° C., PP (polypropylene) has a melting point of about 160-170° C, PS (polystyrene) has a melting point of about 70-115° C. and PVC (polyvinylchloride) has a melting point of about 75-90° C.

Some means have melting points that are also dependent on the pressure, not just temperature, in which case this must also take be into consideration when one chooses protection means as the pressure in the oil well is normally very high and can vary considerably from one well to another.

In a preferred embodiment the protection means is put on so that it covers, at least, the upper side of the device that shall be protected, i.e. the side that faces upwards in the pipe and which is thereby most exposed to be damaged by objects that fall down from above.

“The upper side of the plug” refers here to the side of the plug that faces upwards towards any falling objects that fall down in the well. It is more preferred to cover all parts of the device that can easily be damaged and it is most preferred that the whole of the outside of the tool/instrument is covered, i.e. that it is completely encapsulated in the protection means. Then, the tool/instrument is protected best, but according to what kind of tool/instrument this is, it is not necessarily favourable or possible to cover it completely so that parts thereof must remain uncovered. Areas of the tool/instrument that are not vulnerable to damages from impacts from falling objects do not need to be covered, of course.

In its simplest embodiment, the protection means is comprised of just one such layer of material that becomes liquid at a given temperature. Then, the material must be relatively solid at the temperatures lower than its melting point for it to stick to the tool/instrument before it reaches its predetermined melting point. When the material becomes liquid, it, and thereby the whole of the protection means, will melt and flow off and make the device ready for use. The advantage with this is that the material flows off in a liquid form when it is no longer needed and does not prevent the application of the device. It can mix in with the other fluids in the well pipe.

Alternatively, the protection means can also comprise other constituent parts that are not heat deactivatable (i.e. in the understanding that the protection means melts and flows off the sensitive equipment). For example, it can comprise a covering outside the protection means in the form of a flexible membrane, or a more solid covering, or other layers of protective materials, such as, for example, a viscous liquid. According to a preferred embodiment of the present invention the protection means is completely or partially covered by a flexible membrane.

According to a preferred embodiment of the invention the material layer is completely or partially covered by a flexible membrane or a solid material. This can then protect the heat deactivated material against the fluids in the well and one can use a somewhat softer material i.e. liquid or partially solid, without this leaking out and losing its covering function. When the material then melts and becomes liquid, the membrane covering will prevent that it flows out and mixes into the fluids that are present in the well, but as it is now in a liquid form the device is still ready to be used. A such flexible membrane or solid material can be manufactured by any membrane material or solid material suited to be used in an oil well. The membrane and the solid material will not melt.

Examples of suitable elastic material are natural materials such as rubber and synthetic materials such as polymers such as polyethylene (in particular with medium or low density) or polypropylene (particularly with high density). Any solid material can be used that is suitable for oil wells.

Alternatively, one can use a disc that can move in the axial direction of the production pipe. According to this embodiment of the present invention the disc will cover the upper side of the device and is free to move in the axial direction of the pipe, while it seals against the pipe wall (the inside wall of the production pipe or alternatively the holder if the plug is placed in a holder). In other words, the disc creates a seal against the wall, but can be moved axially so that it can be forced against and be lifted upwards from the device and can therefore move when it is hit by falling objects or hits against something. Meant by the expression “disc” is a round, disc-formed object that is circular and relatively flat. The choice of materials for the disc is a technical issue, one can use the same materials that are used for other components for equipment in production wells, for example, metals, ceramic materials, different artificial materials such as plastic and glass. The disc can also be flexible and thus be manufactured from the same materials as the membrane according to the invention.

According to an embodiment of the invention where the protection means is completely or partially covered by a flexible membrane or a further solid material, it is preferred that the means is placed so that it covers the upper side of the tool/instrument that shall be protected when it is placed in the well pipe, and the flexible membrane and/or the solid protection means is placed on the top side of said layer of protection means, where said flexible membrane or further solid material is preferably formed as a round disc adapted to the production pipe.

According to a preferred embodiment the protection means in addition to a flexible membrane or a further solid, covering material can comprise a thick, viscous liquid placed so that the liquid is covered by the flexible membrane and/or the additional solid material. The viscous liquid must be placed under the membrane and/or the additional solid material so that it is held in place and the membrane or the additional solid material can then not be permeable to the viscous liquid. The viscous liquid, that can protect the device further, is defined as thick, fluids that have a thick, sticky or paste-like consistency between a solid and a liquid state. Thus, a viscous liquid can be a thick liquid or a gel-like or cream-like mass, or a paste.

In other words, viscous liquids are clearly more solid and slow flowing than water, but not completely solid. Viscous liquids in connection with the present invention will have a viscosity of 0.01-1000 Pa·s, preferably 0.1-500 Pa·s and most preferred 1-100 Pa·s, at the temperature and pressure conditions in the well where the plug shall be used.

Examples of viscous liquids that can be used according to the invention are fat clay, different forms of gels such as, for example, polymer-based gels, different forms of lubrication such as, for example, silicon lubrications, glycerol and different forms of oils such as Castor oil. Thereby, viscous liquids can also be a mixture of different materials, either liquids or liquids with fluids or solid materials mixed in.

A such viscous liquid is especially suited to protect tools and the like against impacts from falling objects as a such layer of this will absorb and distribute point loads from, for example, corners or sharp parts that stick out from the objects that hit, and prevent that the whole force from such an object hits a small point on the tool, which can then disintegrate more easily. By placing a flexible membrane or disc that can be moved in the axial direction on the top thereof, the viscous liquid is sealed in but it is still able to absorb point loads.

According to a preferred embodiment of the invention a dilatant liquid, also called a shear thickening liquid, is used as the viscous liquid. Dilatant liquids do not have a constant viscosity for different shear rates, the viscosity increases with increased application of shear force. In other words, the harder and quicker the blows are supplied, the more the dilatant liquid will thicken and harden and distribute the force from the blows throughout the whole of the liquid. One will then choose a dilatant liquid which is normally liquid at the pressure where the device shall be used at, but which becomes hard at sudden pressure impacts.

As the viscosity of viscous liquids is temperature dependent, one must take into consideration the temperature one can expect in the oil well. As the temperature dependence of the viscosity of viscous liquids is known, this will not be a problem for one skilled in the arts.

According to an embodiment of the invention the protection means, which is solid or partially solid at the temperatures in the upper part and liquid at the temperatures in the lower part of the well, can also be a viscous liquid which means that it is partially softened and solid at the temperatures in the upper part, and liquid at the temperatures in the lower part of the oil well. Normally one then needs a flexible membrane or disc as described above to hold the viscous liquid in place around the object in the form of the tool/instrument. This is especially preferred, as a viscous liquid as explained above can distribute point loads better than a solid material and by being temperature deactivated advantages are achieved by the invention.

According to a preferred application of the present method the heat deactivatable protection means is placed on the tool/instrument before the assembly is lowered down in the well pipe, either in connection with the production of the device or it can be installed afterwards. This can be done after the tool/instrument itself is completely produced, as a post-installation, or as a part of the production and assembly of the tool/instrument, for example, as a part of the production of a piece of production pipe. 

1. Method to protect sensitive equipment against impact damages, such as tools and instruments and the like which shall be lowered down in a well pipe in a hydrocarbon-carrying formation, characterised in that onto the equipment is added a layer of a protection means that is solid or partially solid when added and also at the temperatures in an upper part of the well pipe, while it melts and becomes liquid and flows off the equipment at the temperatures that exist in the lower part of the well pipe in which the equipment shall be applied.
 2. Method according to claim 1, characterised in that the layer of protection means is placed so that it covers at least an upper side of the equipment that shall be protected and preferably the whole of the outside of the equipment.
 3. Method according to one of the claims claim 1-2, characterised in that the protection means that covers the equipment is completely or partially covered by a flexible membrane or a further solid material.
 4. Method according to any of the claims 1-3, characterised in that the protection means is covered by a further solid material in the form of a round disc adapted to the diameter dimensions of the production pipe.
 5. Method according to any of the preceding claims, characterised in that the protection means that is put on the equipment is in the form of a viscous liquid placed so that it is covered by the flexible membrane and/or the additional solid disc-formed material.
 6. Method according to any of the preceding claims, characterised in that when used for protection of equipment and instruments in a pipe section that carries a crushable plug, its release mechanism for crushing of the plug is covered by a protection means before the pipe section is lowered down in the well pipe.
 7. Method according to any of the preceding claims, characterised in that the choice of protection means is made according to measurements and knowledge about the temperature profile of the formation the well pipe is led down through, as one chooses a protection means that is solid at the relevant temperature at the surface and in the top part of the well pipe and which melts into a liquid form when the equipment comes further down in the well.
 8. Method according to any of the preceding claims, characterised in that protection means being applied are different types of waxes, fats or oils or mixtures of these, or metals or metal alloys, said means which are in solid or partially solid form in the upper parts of the well, but which become liquid in the deeper parts of the well.
 9. Method according to any of the preceding claims, characterised in that a protection means is applied chosen from beeswax, carnauba wax, solid palm oil, stearin, or mixtures of petroleum waxes such as paraffin waxes or mixtures of such materials.
 10. Method according to any of the preceding claims, characterised in that a protection means is used that is chosen from tin (Sn), or alloys of different metals having a relatively low melting point, such as different eutectic alloys of one or more of the metals bismuth, lead, tin, indium and cadmium, Lipowitz alloy, cerrolow, Rose's metal and Field's metal.
 11. Method according to any of the preceding claims, characterised in that the protection means is chosen from plastic materials such as HDPE (polyethylene with a high density) with a melting point of about 130° C., LDPE (polyethylene with a low density), PP (polypropylene), PS (polystyrene) and PVC (polyvinylchloride).
 12. Protection means for the protection of sensitive equipment against impact damages, such as tools and instruments and the like that shall be lowered down in well pipes in a hydrocarbon-carrying formation, characterised in that the means is a material that is solid or partially solid at the temperatures in the upper part of the well pipe and liquid at the temperatures in the lower part of the oil well where the device that shall be protected shall be used.
 13. Protection means according to claim 12, characterised in that the choice of protection means is adapted to the temperature profile of the formation through which the well pipe is led, as one choses a protection means that is solid at the relevant temperatures at the surface and in the upper part of the well pipe and which melts into a liquid form when the equipment comes further down the well.
 14. Protection means according to any of the claims 12-13, characterised in that it is composed of different types of wax, fats or oils or mixtures of such materials, or metals or metal alloys, said means which are in a solid or partially solid form in the upper part of the well, but which become liquid in the deeper part of the well.
 15. Protection means according to any of the claims 12-14, characterised in that a protection means is applied chosen from beeswax, carnauba wax, solid palm oil, stearin, or mixtures of petroleum waxes such as paraffin waxes or mixtures of such materials.
 16. Protection means according to any of the claims 12-15, characterised in that the protection means is metals or alloys of different metals having a relatively low melting point, such as different eutectic alloys of one or more of the metals bismuth, lead, tin, indium and cadmium, Lipowitz alloy, cerrolow, Rose's metal and Field's metal.
 17. Protection means according to any of the preceding claims 12-16, characterised in that the protection means is of plastic materials such as HDPE (polyethylene with a high density), LDPE (polyethylene with a low density), PP (polypropylene), PS (polystyrene) and PVC (polyvinylchloride).
 18. Application of protection means according to the preceding claims to protect sensitive equipment that is placed in a production pipe in an oil well against damage from the impact of falling objects in the production pipe, and/or against damage from collision with the production pipe or objects in this when the equipment is lowered down in the well pipe.
 19. Application of protection means according to the preceding claims, where the means is put onto the equipment before it is lowered down in the well pipe, either in connection with the production of the equipment or as a post-installation.
 20. Application of protection means for the protection of equipment that shall be lowered through a vertical part of the well pipe and further into a horizontal part of the well pipe where the equipment shall be fitted.
 21. Application of protection means for the protection of sensitive equipment that is placed in a production pipe in an oil well, the equipment is a plug for pressure testing where said plug is preferably a glass or ceramic plug. 